1989 Chrysler NY Landau- How to remove trim on rear door

I recently had the landau roof or cap on this car redone but in a different color. Now I need to remove the trim piece on the rear doors to change the color there. I've removed the three screws that are available from inside the jamb but there is an attachment device inside that I cannot get at. I cannot see a screw or a nut there nor anyway to get at it even if the window were out. Can anyone help here?? Thanks.